1. Field of the Invention
The present invention relates to an electronic fuel injection apparatus for a diesel engine, and in particular to an electronic fuel injection apparatus for a diesel engine which determines a target injection quantity based on a driving state of a vehicle.
2. Description of the Related Art
In a vehicle comprising an automatic transmission of torque converter type, an engine load is heavier when a gearshift position is in a driving position such as D (drive) position or R (reverse) position than when the gearshift position is in a non-driving position such as N (neutral) position or P (parking) position, so that the rotational speed of the engine slows down.
Therefore, a diesel engine comprising an electronically controlled fuel injection apparatus has a sensor (switch) for detecting the gearshift position of a gearshift lever, where a target injection quantity when the gearshift position is in the driving position is set to a driving target injection quantity (shown by Qdr.sub.-- dsr of a dotted line in FIG. 1A) which is obtained by adding a predetermined correction quantity corresponding to an amount of such an increased load as mentioned above to a basic target injection quantity (Qbase in FIG. 1A) which is determined based on the driving state such as an engine speed or a load (mainly an accelerator opening), thereby compensating for the slow-down of the engine speed.
It is to be noted that the target injection quantity is to be finally obtained by adding thereto a correction quantity which takes into account parameters such as an intake temperature, water temperature, and intake pressure of the engine.
However, in response to a gearshift lever operation shown in FIG. 1B, the actual gear action, especially from the non-driving position to the driving position causes a delay as shown in FIG. 1C.
This is because the gearshift operation is performed by utilizing the pumping pressure of an oil pump disposed within a transmission to clutch clutch plates, which causes a delay in increasing the pumping pressure.
On the other hand, a sensor for detecting the gearshift position immediately produces a gear action signal in response to the gearshift lever operation. A controller provided within the electronic injection apparatus, in response to the gear action signal, immediately corrects the basic target injection quantity (Qbase) to the above-mentioned driving target injection quantity (Qdr.sub.-- dsr).
As a result, although the actual gearshift position is not in the driving position, the injection quantity is solely increased, thereby causing an instantaneous rise of engine speed or the generation of smoke at the time of gearshift operation.
In this case, a time lag may also be preset from the time when the gear action signal is received to the time when the injection quantity is corrected in the increasing direction in conformity with the completion timing of the gear action. However, even during the gear action, the load increases for enhancing the pumping pressure of the oil pump as mentioned above, so that the preset time lag may cause the engine speed to slow down.